Prosthetic implant support structure

ABSTRACT

A prosthetic system that includes a prosthetic implant and a support structure secured to an inner surface of the cavity in the end of the bone is disclosed. The support structure defines a channel that extends through the length of the support structure. The prosthetic implant is received in the channel, and a portion of the prosthetic implant is secured to an inner surface of the channel by an adhesive. The stem of the prosthesis beyond the channel may be cemented or uncemented. The support structure may have an approximately funnel shape. The support structure may be a hollow porous cylindrical sleeve. The support structure may comprise a pair of partially hemispherical components arranged in spaced apart relationship thereby defining a channel between the pair of components. The support structure may comprise a plurality of pedestals secured to the inner surface of the cavity of the bone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No. 10/225,774filed Aug. 22, 2002 now abandoned which claims the benefit of U.S.Provisional Patent Application No. 60/315,148 filed Aug. 27, 2001.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to prosthetic devices for implantation within abone, and more particularly to support structures that are affixed to abone and that support prosthetic implants.

2. Description of the Related Art

The replacement of joints, such as the shoulder, hip, knee, ankle andwrist, with prosthetic implants has become widespread. One problemcommonly encountered by surgeons replacing joints is the loss of strongbone stock near the joint being replaced. Defects in a bone adjacent ajoint, such as the hip or knee, can occur due to wear and arthritis ofthe joint, congenital deformity, and following the removal of a failedprosthetic implant. Defects can be of a cavitary contained type orsegmental and uncontained. Because such bone defects are quite common,various methods have been proposed for minimizing the adverse effects ofsuch bone defects on joint replacement procedures.

It is known to use bone graft to prepare a support surface for aprosthesis, either with or without the use of cement. A bone graftingprocedure is often used where there is an appreciable loss of strongbone stock, as is often the case in revision surgery where a previouslyimplanted prosthesis is replaced with a new prosthesis. The supportsurface prepared with bone graft may be made up entirely of bone graftto substantially surround a prosthesis, or the support surface may bemade up of bone graft and the natural bone at the implantation site (forinstance, where bone graft is used to fill a relatively small void inthe natural bone where the bone is otherwise intact). Bone grafttypically includes crushed bone (cancellous and cortical), or acombination of these and synthetic biocompatible materials. Bone graftof this type is intended to stimulate growth of healthy bone. Examplesof bone graft materials and related materials can be found in U.S. Pat.Nos. 5,972,368, 5,788,976, 5,531,791, 5,510,396, 5,356,629, 4,789,663and 4,678,470. Bone graft may be positioned in a bone cavity by variousmethods such as those described in U.S. Pat. Nos. 6,142,998, 6,013,080and 5,910,172. The use of bone graft to prepare a support surface for aprosthesis does have certain disadvantages as bone graft may not bereadily available in all areas and the devices used to deliver bonegraft can be quite cumbersome.

In the presence of bone deficiency, stemmed components are also oftenused as a method to augment prosthesis fixation during complex primaryor revision knee and hip arthroplasty. These stems may be cemented oruncemented; however, the most common method of fixation during revisionknee arthroplasty is the use of an uncemented stem combined with cementfixation of the prosthesis in the metaphyseal region. However, due tothe large variation of bone quality, interdigitation of bone cement intothe metaphyseal region is often suboptimal such that cement fixation ofthe stem in the bone cavity is necessary. While cement fixation of thestem provides for improved prosthesis fixation, it does havedisadvantages. For example, one recognized problem with the use of acemented stem is that the transfer of stress from the implant to thebone is abnormal. Instead of a normal loading of the bone primarily atthe end of the bone near the joint surface, the bone is loaded moredistally where the stem of the implant is affixed to the bone. Thisresults in the well known phenomenon called “stress shielding” in whichthe load (i.e., stress) bypasses or “unloads” the end of the jointsurface portion of the bone.

In the presence of severe bone deficiency, the diaphyseal region of thebone is often deficient or absent and requires the use of bone graft orunique prosthetic designs to achieve adequate prosthesis fixation duringcomplex primary or revision knee and hip arthroplasty. The use of largestructural allografts to restore bone stock requires a sophisticatedbone banking system and is associated with the potential transmission ofviral or bacterial pathogens. Furthermore, the difficulties with sizingand bone graft preparation are cumbersome and inexact.

When the bone deficiency occurs at the end surface of a bone, prostheticimplant augmentation devices are also often used. Typically, thesedevices comprise an implant body and a spacer that is attached to theimplant body to form a bearing surface on the implant. The implant isaffixed to the bone with the bearing surface resting on the end of thebone, essentially acting as a replacement for lost bone. U.S. Pat. Nos.5,480,445, 5,387,241, 5,152,797 and 5,019,103 show examples of suchdevices. While these types of implant augmentation devices provide onesolution to the problems associated with the implantation of aprosthesis in the end surface of a bone with inadequate bone stock,these implant augmentation devices can only be used with specificimplants available from selected implant manufacturers.

In the context of hip arthroplasty, oversized acetabular components andmorselized bone grafts have been used to restore bone deficiencies, butlarger defects have in the past been associated with a high failure ratedespite efforts at reconstruction using large solid structuralallografts or custom acetabular components. These devices gain supportagainst the residual bone of the pelvis but often lack adequate bonysupport for long term mechanical durability.

Therefore, there is a need for alternative prosthetic implant supportstructures that do not rely on the use of large amounts of bone graft orcumbersome bone graft delivery devices. There is also a need forprosthetic implant support structures that can eliminate the need tocement the distal portion of the stem of an implant to the inner surfaceof a bone cavity. In addition, there is a need for prosthetic implantsupport structures that can be used with a wide variety of prostheticimplants obtained from any number of different implant manufacturers.Furthermore, there is a need for a prosthetic implant system thatoptimizes implant support on intact host bone with minimal removal ofresidual host bone and that encourages bone ingrowth and attachment overas large a surface area as possible.

SUMMARY OF THE INVENTION

The foregoing needs are met by a prosthetic system according to theinvention that is implanted in a cavity in an end of a bone. Theprosthetic system includes a prosthetic implant and a support structuresecured to an inner surface of the cavity in the end of the bone. Thesupport structure defines an axial channel that extends through thelength of the support structure. The prosthetic implant is received inthe channel of the support structure, and a portion of the prostheticimplant is secured to an inner surface of the channel of the supportstructure by an adhesive.

In one version of the invention, the support structure comprises ahollow sleeve having a sloped outer surface such that the length of afirst perimeter of one end of the sleeve is greater than the length of asecond perimeter at an opposite end of the sleeve. Such a supportstructure may have an approximately funnel shape. At the junction of themetaphysis and diaphysis of a bone such as the femur or tibia, the bonedefect is often funnel shaped. Accordingly, a funnel shaped supportstructure in accordance with the invention can be impacted into thedistal femur or proximal tibia so that the external geometry of thefunnel shaped support structure is firmly wedged in themetaphyseal-diaphyseal junction of the bone. The internal portion of thefunnel shaped support structure provides an access channel that allowspassage of the stem extending from a traditional prosthesis of anyprosthetic design or manufacturer. The stem of the prosthesis iscemented to the inner surface of the access channel using bone cement,and the stem extension beyond the funnel shaped support structure may becemented or uncemented.

In another version of the invention, the support structure comprises ahollow porous cylindrical sleeve. The sleeve can be inserted into alarge cavernous diaphyseal bone defect or can be used as a replacementfor segmental or complete diaphyseal bone deficiency. The sleeve can bea number of different sizes and lengths so that a surgeon can pick theappropriate sized sleeve for the patient after intraoperative assessmentand thereby avoid difficulties of size mismatch and bone graftcontouring. The sleeve can accommodate any number of prosthetic designsand can achieve fixation to remaining host tissue by soft tissue or boneingrowth. A stem of a prosthesis is fixed within the sleeve by use ofbone cement, and the stem of the prosthesis beyond the sleeve may becemented or uncemented.

In yet another version of the invention, the support structure comprisesa pair of components arranged in spaced apart relationship therebydefining a channel between the pair of components. The support structuremay be based on hemispherical shapes (such as a configurationapproximating a quarter of a sphere) which are provided in a range ofsizes for the creation of a prosthetic foundation for support ofstandard tibial, femoral, or acetabular components. While this supportstructure is particularly useful in the acetabulum and hip, the supportstructure is appropriate for all joints undergoing prostheticreplacement with a wide range of shapes and sizes necessary formanagement of defects in different locations. The support structure iscompatible with a range of standard implant designs currently availablefrom a variety of manufacturers. The interface between the pair ofcomponents and the prosthetic implant is cemented with bone cement. Allsurfaces against host bone may be uncemented and are available for boneingrowth into porous materials used for the components. Optionally,morselized cancellous bone may be placed into fenestrations in the pairof components and supplemental screw fixation of the pair of componentsto bone may be used to encourage bone ingrowth and secure fixation tohost bone over the long term.

In still another version of the invention, the support structurecomprises a plurality of pedestals secured to the inner surface of thecavity of the bone. Each pedestal comprises a flat body section and astem section extending substantially perpendicularly from the bodysection. The stem section of each pedestal is secured to the innersurface of the cavity of the bone, and the flat body sections of thepedestals are secured to a portion of a bearing surface of theprosthetic implant. The support structure may further comprise bonegraft material surrounding the plurality of pedestals. In one form, thepedestals and the bone graft material are arranged in a circulararrangement whereby the channel that extends through the length of thesupport structure is circular. A stem of a prosthesis is fixed withinthe channel by use of bone cement, and the stem of the prosthesis beyondthe channel may be cemented or uncemented.

It is therefore an advantage of the present invention to provideprosthetic implant support structures that do not rely on the use oflarge amounts of bone graft or cumbersome bone graft delivery devices.

It is another advantage of the present invention to provide prostheticimplant support structures that can eliminate the need to cement thedistal portion of the stem of an implant to the inner surface of a bonecavity.

It is a further advantage of the present invention to provide prostheticimplant support structures that can be used with a wide variety ofprosthetic implants obtained from any number of different implantmanufacturers.

It is yet another advantage of the present invention to provide aprosthetic implant system that optimizes implant support on intact hostbone with minimal removal of residual host bone and that encourages boneingrowth and attachment over as large a surface area as possible.

These and other features, aspects, and advantages of the presentinvention will become better understood upon consideration of thefollowing detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of one embodiment of a prostheticimplant support structure according to the invention being placed in atibia;

FIG. 2 is a cross-sectional view of the prosthetic implant supportstructure of FIG. 1 as placed in a tibia;

FIG. 3 is a side view of a prosthetic implant being placed in theprosthetic implant support structure in the tibia as shown in FIG. 2;

FIG. 4 is a cross-sectional view of the prosthetic implant as placed inthe prosthetic support structure in the tibia as shown in FIG. 3;

FIG. 5 is a side view of another embodiment of a prosthetic implantsupport structure according to the invention;

FIG. 6 is a cross-sectional view of the prosthetic implant supportstructure of FIG. 5 taken along line 6-6 of FIG. 5;

FIG. 7 is another cross-sectional view of the prosthetic implant supportstructure of FIG. 5 taken along line 7-7 of FIG. 5;

FIG. 8 is cross-sectional view of the prosthetic implant supportstructure of FIG. 5 being placed in a femur;

FIG. 9 is a cross-sectional view of the prosthetic support structure ofFIG. 5 as placed in the femur as shown in FIG. 8;

FIG. 10 is a cross-sectional view of a prosthetic implant being placedin the prosthetic support structure of FIG. 5 as placed in the femur asshown in FIG. 9;

FIG. 11 is a cross-sectional view of a prosthetic implant placed in theprosthetic support structure of FIG. 5 as placed in the femur as shownin FIG. 9;

FIG. 12 is an exploded perspective view of yet another embodiment of aprosthetic implant support structure according to the invention beingplaced in a tibia;

FIG. 13 is a perspective view of the prosthetic implant supportstructure of FIG. 12 as placed in a tibia;

FIG. 14 is an exploded perspective view of a prosthetic implant beingplaced in the prosthetic support structure of FIG. 12 as placed in thetibia as shown in FIG. 13;

FIG. 15 is a perspective view of a prosthetic implant placed in theprosthetic support structure of FIG. 12 as placed in the tibia as shownin FIG. 13;

FIG. 16 is cross-sectional view of a prosthetic implant placed in theprosthetic support structure as placed in the tibia taken along line16-16 of FIG. 15;

FIG. 17 is an exploded perspective view of an acetabular cup of a hipprosthesis being placed in still another embodiment of a prostheticimplant support structure according to the invention secured in theacetabular cavity of a hip;

FIG. 18 is an exploded perspective view of an acetabular cup of a hipprosthesis being placed in a further embodiment of a prosthetic implantsupport structure according to the invention secured in the acetabularcavity of a hip;

FIG. 19 is an exploded perspective view of an acetabular cup of a hipprosthesis being placed in yet another embodiment of a prostheticimplant support structure according to the invention secured in theacetabular cavity of a hip;

FIG. 20 is an exploded perspective view of an acetabular cup of a hipprosthesis being placed in still another embodiment of a prostheticimplant support structure according to the invention secured in theacetabular cavity of a hip;

FIG. 21 is a cross-sectional view of an acetabular cup of a hipprosthesis placed in the prosthetic implant support structure of FIG. 19taken along line 21-21 of FIG. 19;

FIG. 22 is a cross-sectional view of an acetabular cup of a hipprosthesis placed in the prosthetic implant support structure of FIG. 20taken along line 22-22 of FIG. 20;

FIG. 23 is a cross-sectional view of an acetabular cup of a hipprosthesis placed in the prosthetic implant support structure of FIG. 18taken along line 23-23 of FIG. 18; and

FIG. 24 is a cross-sectional view of an acetabular cup of a hipprosthesis placed in the prosthetic implant support structure of FIG. 17taken along line 24-24 of FIG. 17.

It should be understood that the drawings are not necessarily to scaleand that the embodiments are sometimes illustrated by diagrammaticrepresentations and fragmentary views. In certain instances, detailswhich are not necessary for an understanding of the present invention orwhich render other details difficult to perceive may have been omitted.It should be understood, of course, that the invention is notnecessarily limited to the specific embodiments illustrated herein.

Like reference numerals will be used to refer to like or similar partsfrom Figure to Figure in the following description of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a prosthetic system that includes aprosthetic implant and a support structure secured to an inner surfaceof the cavity in the end of the bone. The prosthetic system and themethods for its use are illustrated and described herein with referenceto the replacement of a hip joint or a knee joint. However, it should beunderstood that the methods and prosthetic systems according to theinvention can be used in the repair of any bone or in connection withthe implantation of prosthetic devices at or in any bone in the body,adjacent to or remote from any joint, including without limitation thehip, knee and spinal joints. Further, the methods and prosthetic systemsaccording to the invention can be used in primary surgery, in which aprosthesis is being used to reconstruct a joint for the first time, aswell as in revision surgery, in which a previously-implanted prosthesisis being replaced with another prosthesis. Press fit, cement or otherfixation techniques can be employed in conjunction with the methods andprosthetic systems according to the invention.

Looking first at FIGS. 1 to 4, there is shown a prosthetic system thatincludes a tibial implant 20 and a funnel shaped sleeve 40 that issecured to the inner surface 4 of the medullary canal (cavity) 3 of theend portion 5 of a tibia 2. The tibial implant 20, which is best shownin FIG. 3, has a body portion 21 and a stem 24 which extends outwardfrom the body portion 21. The body portion 21 includes a bearing surface22 that is typically affixed to the end surface 6 of the end portion 5of the tibia. The outer limits of the bearing surface 22 define aperimeter 23. The stem 24 of the tibial implant 20 has a distal portion25 and an outer surface 26. The tibial implant 20 is of conventionaldesign and articulates with a femoral knee prosthesis (not shown) as iswell known in the art.

Referring to FIG. 1, there is shown the tibia 2 and the funnel shapedsleeve 40 that supports the tibial implant 20 as will be describedbelow. From FIG. 1, it can be seen that at the junction of themetaphysis and diaphysis of the tibia 2, there is a funnel shaped bonedefect 7 which can be fashioned to provide a large surface area of bone.The funnel shaped sleeve 40 is impacted into the end portion 5 of thetibia 2 so that the external geometry of the funnel shaped sleeve 40 isfirmly wedged into the metaphyseal-diaphyseal junction as shown in FIG.2.

The funnel shaped sleeve 40 defines an axial access channel 46 thatextends through the length of the funnel shaped sleeve 40. The funnelshaped sleeve 40 has a top end surface 41, an outer surface 42, and aninner surface 47 of the access channel 46. In the version of the funnelshaped sleeve 40 shown, the outer surface 42 of the funnel shaped sleeve40 is sloped such that the length of a top end perimeter 43 of thefunnel shaped sleeve 40 is greater than the length of a bottom endperimeter 44 at an opposite end of the funnel shaped sleeve 40. Theinner surface 47 of the access channel 46 may be similarly sloped ifdesired. The funnel shaped sleeve 40 may be formed from a metal alloysuch as titanium alloys (e.g., titanium-6-aluminum-4-vanadium),cobalt-chromium alloys, stainless steel alloys and tantalum alloys;nonresorbable ceramics such as aluminum oxide and zirconia;nonresorbable polymeric materials such as polyethylene; or compositematerials such as carbon fiber-reinforced polymers (e.g., polysulfone).Preferably, the funnel shaped sleeve 40 is formed from a metal alloy.

The outer surface 42 of the funnel shaped sleeve 40 may be provided witha metallic texture coating which provides a textured surface so as toattain the desired fixation (by way of tissue ingrowth) between thefunnel shaped sleeve 40 and the inner surface 4 of the medullary canal(cavity) 3 of the end portion 5 of the tibia 2 within which the funnelshaped sleeve 40 is implanted. The inner surface 47 of the accesschannel 46 of the funnel shaped sleeve 40 has a rough or corrugatedsurface finish to facilitate the interdigitation of bone cement.Likewise, the top end surface 41 of the funnel shaped sleeve 40 has arough or corrugated surface finish to facilitate the interdigitation ofbone cement. The funnel shaped sleeve 40 may have a variety of shapesand sizes, which vary by height, width and depth. A surgeon can useconventional measurement tools to select the height, width and depth ofthe funnel shaped sleeve 40.

The prosthetic system shown in FIGS. 1 to 4 may be implanted in a boneas follows. First, the end portion 5 of the tibia 2 is inspected andtools (such as a reamer) may be used to clean material out of themedullary canal (cavity) 3 or the bone defect 7 (if any). Once themedullary canal (cavity) 3 and the bone defect 7 have been prepared, thefunnel shaped sleeve 40 is impacted into the end portion 5 of the tibia2 so that the external geometry of the funnel shaped sleeve 40 is firmlywedged into the tibia 2. If desired, conventional bone cement such as anacrylic cement (e.g., polymethyl methacrylate) may be used to secure theouter surface 42 of the funnel shaped sleeve 40 to the inner surface 4of the medullary canal (cavity) 3 of the end portion 5 of a tibia 2.Next, the stem 24 of the tibial implant 20 is moved into the accesschannel 46 of the funnel shaped sleeve 40. As shown in FIG. 4, at leasta portion of the outer surface 26 of the stem 24 of the tibial implant20 is secured to the inner surface 47 of the access channel 46 of thefunnel shaped sleeve 40 with a suitable adhesive such as bone cement 38(e.g., polymethyl methacrylate). Optionally, the distal portion 25 ofthe tibial implant 20 (which extends beyond the length of the funnelshaped sleeve 40) may be secured to the inner surface 4 of the medullarycanal (cavity) 3 of the tibia 2 with a suitable adhesive such as bonecement 38 (e.g., polymethyl methacrylate).

Looking at FIG. 4 (which shows the tibial implant 20 and the funnelshaped sleeve 40 implanted in the tibia 2), several aspects of theinvention can be described. For example, it can be seen that a portionof the bearing surface 22 of the tibial implant 20 is secured by cement38 to the top end surface 41 of the funnel shaped sleeve 40 adjacent theend portion 5 of the tibia 2. The top end surface 41 of the funnelshaped sleeve 40 provides a rough or corrugated surface finish tofacilitate the interdigitation of bone cement and provides an attachmentsurface for the tibial implant 20 where bone stock has been lost. Also,the region near the perimeter 23 of the bearing surface 22 of the tibialimplant 20 is secured by cement 38 to the end surface 6 of the endportion 5 of the tibia 2. This provides for additional support for thetibial implant 20. The simultaneous attachment of the bearing surface 22of the tibial implant 20 to the top end surface 41 of the funnel shapedsleeve 40 and to the end surface 6 of the end portion 5 of the tibia 2is possible because the funnel shaped sleeve 40 is positioned in thecavity 3 of the tibia 2 such that the funnel shaped sleeve 40 does notextend beyond a plane defined by the end surface 6 of the end portion 5of the tibia 2.

Because the funnel shaped sleeve 40 is not an integral component of thetibial implant 20, the funnel shaped sleeve 40 can be used with anystemmed prosthesis regardless of manufacturer or prosthetic design.Further, it should be noted that the example given in FIGS. 1 to 4relates to use of the funnel shaped sleeve 40 in the proximal tibia;however, another common site where the funnel shaped sleeve 40 would befrequently used is the distal femur. Still other anatomic sites wouldinclude any joint that undergoes prosthetic arthroplasty when there is asignificant metaphyseal bone deficiency.

In the presence of severe bone deficiency, the diaphyseal region of abone is often deficient or absent and often requires the use of bonegraft or unique prosthetic designs to achieve adequate prosthesisfixation during complex primary or revision knee and hip arthroplasty.As detailed above, the use of large structural allografts to restorebone stock requires a sophisticated bone banking system and isassociated with the potential transmission of viral or bacterialpathogens. Furthermore, the difficulties with sizing and bone graftpreparation are cumbersome and inexact. The advantages of minimizingdisease transmission by minimizing use of allograft material and reducedoperative times can be achieved with another prosthetic system accordingto the invention as shown in FIGS. 5 to 11. The prosthetic system allowsfor the insertion of a cylindrical porous sleeve into a large cavernousdiaphyseal bone defect and also allows for the replacement of asegmental or complete diaphyseal bone deficiency.

Referring now to FIGS. 5 to 11, there is shown a prosthetic system thatincludes a femoral implant 28 and a cylindrically shaped sleeve 50 thatis secured to the inner surface 10 of the medullary canal (cavity) 9 ofa femur 8. The femoral implant 28, which is best shown in FIG. 10, has abody portion 29 and a stem 32 which extends outward from the bodyportion 29. The body portion 29 includes a bearing surface 30 that istypically affixed to the end surface 12 of the end portion 11 of thefemur 8. The outer limits of the bearing surface 30 define a perimeter31. The stem 32 of the femoral implant 28 has a distal portion 33 and anouter surface 34. The femoral implant 28 is of conventional design andis secured for movement within an acetabular cup (not shown) as is wellknown in the hip replacement art.

Referring to FIG. 8, there is shown the femur 8 and the cylindricalsleeve 50 that supports the femoral implant 28 as will be describedbelow. From FIG. 8, it can be seen that at the diaphyseal region 13 ofthe femur 8, there is a bone defect. The cylindrical sleeve 50 isimpacted into the cavity 9 of the femur 8 so that the external geometryof the cylindrical sleeve 50 is firmly wedged into the diaphyseal region13 of the femur as shown in FIG. 9.

The cylindrical sleeve 50 defines an axial access channel 57 thatextends through the length of the cylindrical sleeve 50. The cylindricalsleeve 50 has a top end surface 52, an outer surface 54, and an innersurface 58 of the access channel 57. The cylindrical sleeve 50 has acylindrical upper section 51 having a first outside diameter and acylindrical lower section 55 having a second outside diameter less thanthe first outside diameter. The access channel 57 may be cylindrical oroptionally, the access channel 57 may be configured to accept variousimplant stem designs. For example, it can be seen from FIG. 6 that theaccess channel 57 in the upper section 51 of the cylindrical sleeve 50has an approximately oval cross-section and from FIG. 7 that the accesschannel 57 in the lower section 55 of the cylindrical sleeve 50 has anapproximately circular cross-section. The cylindrical sleeve 50 may beformed from a porous metal alloy such as titanium alloys (e.g.,titanium-6-aluminum-4-vanadium), cobalt-chromium alloys, stainless steelalloys and tantalum alloys; nonresorbable porous ceramics such asaluminum oxide and zirconia; nonresorbable porous polymeric materialssuch as polyethylene; or porous composite materials such as carbonfiber-reinforced polymers (e.g., polysulfone). Preferably, thecylindrical sleeve 50 is formed from a porous metal alloy.

The outer surface 54 of the cylindrical sleeve 50 may also be providedwith a metallic texture coating which provides a textured surface so asto attain the desired fixation (by way of tissue ingrowth) between thecylindrical sleeve 50 and the inner surface 10 of the medullary canal(cavity) 9 of the femur 8 within which the cylindrical sleeve 50 isimplanted. The inner surface 58 of the access channel 57 of thecylindrical sleeve 50 has a rough or corrugated surface finish tofacilitate the interdigitation of bone cement. Likewise, the top endsurface 52 of the cylindrical sleeve 50 has a rough or corrugatedsurface finish to facilitate the interdigitation of bone cement. Thecylindrical sleeve 50 may comprise any number of different sizes andlengths so that a surgeon is able to pick the appropriate sized sleevefor the patient after intraoperative assessment and thereby avoiddifficulties of size mismatch and bone graft contouring. A surgeon canuse conventional measurement tools to select the length and width of thecylindrical sleeve 50.

The prosthetic system shown in FIGS. 5 to 11 may be implanted in a boneas follows. First, the cavity 9 of the femur 8 is inspected and tools(such as a reamer) may be used to clean material out of the medullarycanal (cavity) 9 or the bone defect (if any). Once the medullary canal(cavity) 9 and the bone defect have been prepared, the cylindricalsleeve 50 is impacted into the femur 2 so that the external geometry ofthe cylindrical sleeve 50 is firmly wedged into the femur 8. If desired,conventional bone cement such as an acrylic cement (e.g., polymethylmethacrylate) may be used to secure the outer surface 54 of thecylindrical sleeve 50 to the inner surface 10 of the medullary canal(cavity) 9 of the femur 8. Next, the stem 32 of the femoral implant 28is moved into the access channel 57 of the cylindrical sleeve 50. Asshown in FIG. 11, at least a portion of the outer surface 34 of the stem32 of the femoral implant 28 is secured to the inner surface 58 of theaccess channel 57 of the cylindrical sleeve 50 with a suitable adhesivesuch as bone cement 38 (e.g., polymethyl methacrylate). Implant fixationwithin the sleeve 50 is achieved by cement interdigitation into therough or corrugated surface finish of the inner surface 58 of the accesschannel 57 of the cylindrical sleeve 50 or into the porous structure ofthe sleeve. Optionally, the distal portion 33 of the femoral implant 28(which extends beyond the length of the cylindrical sleeve 50) may besecured to the inner surface 10 of the medullary canal (cavity) 9 of thefemur 8 with a suitable adhesive such as bone cement 38 (e.g.,polymethyl methacrylate).

Looking at FIG. 11 (which shows the femoral implant 28 and thecylindrical sleeve 50 implanted in the femur 8), several aspects of theinvention can be described. For example, it can be seen that a portionof the bearing surface 30 of the femoral implant 28 is secured by cement38 to the top end surface 12 of the cylindrical sleeve 50 adjacent theend portion 11 of the femur 8. The top end surface 52 of the cylindricalsleeve 50 provides a rough or corrugated surface finish to facilitatethe interdigitation of bone cement and provides an attachment surfacefor the femoral implant 28 where bone stock has been lost. Also, theregion near the perimeter 31 of the bearing surface 30 of the femoralimplant 28 is secured by cement 38 to the end surface 12 of the endportion 11 of the femur 8. This provides for additional support for thefemoral implant 28. The simultaneous attachment of the bearing surface30 of the femoral implant 28 to the top end surface 52 of thecylindrical sleeve 50 and to the end surface 12 of the end portion 11 ofthe femur 8 is possible because the cylindrical sleeve 50 is positionedin the cavity 9 of the femur 8 such that the cylindrical sleeve 50 doesnot extend beyond a plane defined by the end surface 12 of the endportion 11 of the femur 8.

Because the cylindrical sleeve 50 is not an integral component of thefemoral implant 28, the cylindrical sleeve 50 can be used with anystemmed prosthesis regardless of manufacturer or prosthetic design. Thesleeve can accommodate any number of prosthetic designs and achievesfixation to remaining host tissue by soft tissue or bone ingrowth.Further, it should be noted that the example given in FIGS. 5 to 11relates to use of the cylindrical sleeve 50 in the proximal femur;however, another common site where the cylindrical sleeve 50 would befrequently used is the proximal tibia. Still other anatomic sites wouldinclude any joint that undergoes prosthetic arthroplasty when there is asignificant diaphyseal bone deficiency.

Turning now to FIGS. 12 to 16, there is shown a yet another prostheticsystem according to the invention that includes a tibial implant 20 anda periprosthetic support structure, indicated generally at 80, that issecured to the inner surface 4 of the medullary canal (cavity) 3 of theend portion 5 of a tibia 2. The tibial implant 20, which is shown inFIGS. 14 to 16, is identical to the tibial implant 20 that was describedabove with reference to FIGS. 1 to 4 and therefore will not be describedagain.

Referring to FIG. 12, there is shown the tibia 2 and the periprostheticsupport structure 80 that supports the tibial implant 20 as will bedescribed below. From FIG. 12, it can be seen that at the junction ofthe metaphysis and diaphysis of the tibia 2, there is a funnel shapedbone defect 7 which can be fashioned to provide a large surface area ofbone. The components of the periprosthetic support structure 80 areimpacted into the end portion 5 of the tibia 2 so that the components ofthe periprosthetic support structure 80 are firmly wedged into themetaphyseal-diaphyseal junction as shown in FIG. 13.

The periprosthetic support structure 80 comprises a plurality ofpedestals 81 that are impacted into or cemented to the inner surface 4of the medullary canal (cavity) 3 of the end portion 5 of a tibia 2.Each pedestal 81 includes a flat disk shaped body section 82 having atop surface 83 and a stem section 84 extending substantiallyperpendicularly from the body section 82. The stem section 84 optionallyincludes a pointed end section 85 that facilitates impaction into theinner surface 4 of the medullary canal (cavity) 3 of the end portion 5of a tibia 2. Each pedestal 81 may be formed from a metal alloy such astitanium alloys (e.g., titanium-6-aluminum-4-vanadium), cobalt-chromiumalloys, stainless steel alloys and tantalum alloys; nonresorbableceramics such as aluminum oxide and zirconia; nonresorbable polymericmaterials such as polyethylene; or composite materials such as carbonfiber-reinforced polymers (e.g., polysulfone). Preferably, each pedestal81 is formed from a metal alloy. The outer surfaces of each pedestal 81(including the top surface 83) may be provided with a rough orcorrugated surface finish to facilitate the interdigitation of bonecement. The body section 82 of each pedestal 80 may have a variety ofshapes and sizes as long as there exists a generally flat portion onpart of the top surface. The stem section 84 of each pedestal 81 mayalso have various lengths and widths. A surgeon can use conventionalmeasurement tools to select the dimensions of each pedestal 81.

The pedestals 81 may be implanted in a bone as follows to form theperiprosthetic support structure 80. First, the end portion 5 of thetibia 2 is inspected and tools (such as a reamer) may be used to cleanmaterial out of the medullary canal (cavity) 3 or the bone defect 7 (ifany). Once the medullary canal (cavity) 3 and the bone defect 7 havebeen prepared, the stem section 84 of each pedestal 81 is impacted intoor cemented onto the end portion 5 of the tibia 2 to form theperiprosthetic support structure 80. The pedestals 81 may be arranged inany configuration; however, it is preferred that the pedestals 81 arearranged in the circular arrangement shown in FIGS. 13 and 14. Thecircular arrangement of the pedestals 81 creates an access channel thatextends through the length of the periprosthetic support structure 80.Optionally, the periprosthetic support structure 80 may include bonegraft material 39 that is placed around the pedestals 81 to form anaccess channel 86 having an inner surface 87 as shown in FIGS. 13 and14. The bone graft material 39 may selected from known bone graftmaterials and may include crushed bone (cancellous and cortical), or acombination of these and synthetic biocompatible materials. As usedherein, “bone graft” shall mean materials made up entirely of naturalmaterials, entirely of synthetic biocompatible materials, or anycombination of these materials.

After the periprosthetic support structure 80 is formed in a bone, thestem 24 of the tibial implant 20 may be moved into the access channel 86of the periprosthetic support structure 80. As shown in FIG. 16, atleast a portion of the outer surface 26 of the stem 24 of the tibialimplant 20 is secured to the inner surface 87 of the access channel 86of the periprosthetic support structure 80 with a suitable adhesive suchas bone cement 38 (e.g., polymethyl methacrylate). Optionally, thedistal portion 25 of the tibial implant 20 (which extends beyond thelength of the periprosthetic support structure 80) may be secured to theinner surface 4 of the medullary canal (cavity) 3 of the tibia 2 with asuitable adhesive such as bone cement 38 (e.g., polymethylmethacrylate).

Looking at FIGS. 15 and 16 (which show the tibial implant 20 and theperiprosthetic support structure 80 implanted in the tibia 2), severalaspects of the invention can be described. For example, it can be seenthat a portion of the bearing surface 22 of the tibial implant 20 issecured by cement 38 to the top surface 83 of each pedestal 81 of theperiprosthetic support structure 80 adjacent the end portion 5 of thetibia 2. The top end surface 83 of each pedestal 81 of theperiprosthetic support structure 80 provides a rough or corrugatedsurface finish to facilitate the interdigitation of bone cement andprovides an attachment surface for the tibial implant 20 where bonestock has been lost. Also, the region near the perimeter 23 of thebearing surface 22 of the tibial implant 20 is secured by cement 38 tothe end surface 6 of the end portion 5 of the tibia 2. This provides foradditional support for the tibial implant 20. The simultaneousattachment of the bearing surface 22 of the tibial implant 20 to the topend surface 83 of each pedestal 81 of the periprosthetic supportstructure 80 and to the end surface 6 of the end portion 5 of the tibia2 is possible because the periprosthetic support structure 80 ispositioned in the cavity 3 of the tibia 2 such that the periprostheticsupport structure 80 does not extend beyond a plane defined by the endsurface 6 of the end portion 5 of the tibia 2.

Because the periprosthetic support structure 80 is not an integralcomponent of the tibial implant 20, the periprosthetic support structure80 can be used with any stemmed prosthesis regardless of manufacturer orprosthetic design. Further, it should be noted that the example given inFIGS. 12 to 16 relates to use of the periprosthetic support structure 80in the proximal tibia; however, another common site where theperiprosthetic support structure 80 would be frequently used is thedistal femur. Still other anatomic sites would include any joint thatundergoes prosthetic arthroplasty when there is a significantmetaphyseal bone deficiency.

Referring now to FIGS. 17 and 24, there is shown another prostheticsystem according to the invention that includes an acetabular cupimplant 36 having an outer surface 37 and a periprosthetic supportstructure, indicated generally at 60 c, that is secured to the innersurface 16 of the acetabular cavity 15 of a hip bone 14. Theperiprosthetic support structure 60 c comprises two support components61 c having a configuration approximating a quarter of a sphere. Thesupport components 61 c of the periprosthetic support structure 60 c areimpacted, screwed or cemented into the inner surface 16 of theacetabular cavity 15 of a hip bone 14 in a spaced apart relationship.

Each support component 61 c may be formed from a metal alloy such astitanium alloys (e.g., titanium-6-aluminum-4-vanadium), cobalt-chromiumalloys, stainless steel alloys and tantalum alloys; nonresorbableceramics such as aluminum oxide and zirconia; nonresorbable polymericmaterials such as polyethylene; or composite materials such as carbonfiber-reinforced polymers (e.g., polysulfone). Preferably, each supportcomponent 61 c is formed from a metal alloy.

The outer surface 63 c of each support component 61 c may also beprovided with a metallic texture coating which provides a texturedsurface so as to attain the desired fixation (by way of tissue ingrowth)between each support component 61 c and the inner surface 16 of theacetabular cavity 15 of a hip bone 14 within which each supportcomponent 61 c is implanted. The inner surface 64 c of each supportcomponent 61 c has a rough or corrugated surface finish to facilitatethe interdigitation of bone cement. Likewise, the top end surface 62 cof each support component 61 c has a rough or corrugated surface finishto facilitate the interdigitation of bone cement. Each support component61 c also has fenestrations 65 c which can be filled with bone graftmaterial (e.g., morselized cancellous bone).

Each support component 61 c may comprise any number of differentheights, widths and depths so that a surgeon is able to pick theappropriate sized support component for the patient after intraoperativeassessment and thereby avoid difficulties of size mismatch and bonegraft contouring. A surgeon can use conventional measurement tools toselect the size of each support component 61 c. The size, position andorientation of each support component 61 c and the use of supplementalscrew fixation for each support component 61 c is dependent on the sizeand location of the defects in the host bone as well as the quality ofthe bone that remains.

The support components 61 c may be implanted in a bone as follows toform the periprosthetic support structure 60 c. First, the acetabularcavity 15 of the hip bone 14 is inspected and tools (such as a reamer)may be used to clean material out of the acetabular cavity 15. Once theacetabular cavity 15 has been prepared, each support component 61 c isimpacted into or cemented onto the end portion 17 of the acetabularcavity 15 of the hip bone 14 in spaced apart relationship to form theperiprosthetic support structure 60 c. Preferably, each supportcomponent 61 c is not cemented to the hip bone and therefore isavailable for bone ingrowth into the textured outer surface 63 c of thesupport component 61 c. The support components 61 c shown in FIGS. 17and 24 are also screwed into the hip bone 14 using screws 67 (shown inphantom in FIG. 24). The support components 61 c may be arranged in anyconfiguration that creates an access channel 68 c that extends throughthe length of the periprosthetic support structure 60 c. Preferably, thesupport components 61 c are arranged to form a substantiallyhemispherical support structure. It can be seen that placement of thesupport components 61 c precedes placement of any prosthetic jointcomponents.

After the periprosthetic support structure 60 c is constructed in abone, the acetabular cup implant 36 may be placed into the accesschannel 68 c of the periprosthetic support structure 60 c. Placement canoccur either during the same operative procedure as support component 61c placement or can be performed later once bone union to the supportcomponents 61 c has occurred. In either instance, the acetabular cupimplant 36 would be placed only after the acetabulum had beenreconstructed using the support structure 60 c. As shown in FIG. 24, atleast a portion of the outer surface 37 of the acetabular cup implant 36is secured to the inner surface 64 c (shown in phantom) of the accesschannel 68 c of the periprosthetic support structure 60 c with asuitable adhesive such as bone cement 38 (e.g., polymethylmethacrylate). It can be seen that the periprosthetic support structure60 c does not extend beyond a plane defined by the end surface 18 of theend portion 17 of the hip bone 14.

Because the periprosthetic support structure 60 c is not an integralcomponent of the acetabular cup implant 36, the periprosthetic supportstructure 60 c can be used with any acetabular cup implant 36 regardlessof manufacturer or prosthetic design. Further, it should be noted thatthe example given in FIGS. 17 and 24 relates to use of theperiprosthetic support structure 60 c in the acetabular cavity of a hipbone; however, other common sites where the periprosthetic supportstructure 60 c would be frequently used include the tibia and femur.Still other anatomic sites would include any joint that undergoesprosthetic arthroplasty when there is a significant metaphyseal bonedeficiency.

Referring now to FIGS. 18 and 23, there is shown yet another prostheticsystem according to the invention that includes an acetabular cupimplant 36 having an outer surface 37 and a periprosthetic supportstructure, indicated generally at 60 b, that is secured to the innersurface 16 of the acetabular cavity 15 of a hip bone 14. Theperiprosthetic support structure 60 b comprises two support components61 b having a configuration approximating a quarter of a sphere. Thesupport components 61 b of the periprosthetic support structure 60 b areimpacted and/or cemented into the inner surface 16 of the acetabularcavity 15 of a hip bone 14 in a spaced apart relationship.

Each support component 61 b may be formed from a metal alloy such astitanium alloys (e.g., titanium-6-aluminum-4-vanadium), cobalt-chromiumalloys, stainless steel alloys and tantalum alloys; nonresorbableceramics such as aluminum oxide and zirconia; nonresorbable polymericmaterials such as polyethylene; or composite materials such as carbonfiber-reinforced polymers (e.g., polysulfone). Preferably, each supportcomponent 61 b is formed from a metal alloy.

The outer surface 63 b of each support component 61 b may also beprovided with a metallic texture coating which provides a texturedsurface so as to attain the desired fixation (by way of tissue ingrowth)between each support component 61 b and the inner surface 16 of theacetabular cavity 15 of a hip bone 14 within which each supportcomponent 61 b is implanted. The inner surface 64 b of each supportcomponent 61 b has a rough or corrugated surface finish to facilitatethe interdigitation of bone cement. Likewise, the top end surface 62 bof each support component 61 b has a rough or corrugated surface finishto facilitate the interdigitation of bone cement. Each support component61 b also has fenestrations 65 b which can be filled with bone graftmaterial (e.g., morselized cancellous bone).

Each support component 61 b may comprise any number of differentheights, widths and depths so that a surgeon is able to pick theappropriate sized support component for the patient after intraoperativeassessment and thereby avoid difficulties of size mismatch and bonegraft contouring. A surgeon can use conventional measurement tools toselect the size of each support component 65 c. The size, position andorientation of each support component 61 b is dependent on the size andlocation of the defects in the host bone as well as the quality of thebone that remains.

The support components 61 b may be implanted in a bone as follows toform the periprosthetic support structure 60 b. First, the acetabularcavity 15 of the hip bone 14 is inspected and tools (such as a reamer)may be used to clean material out of the acetabular cavity 15. Once theacetabular cavity 15 has been prepared, each support component 61 b isimpacted into or cemented onto the end portion 17 of the acetabularcavity 15 of the hip bone 14 in spaced apart relationship to form theperiprosthetic support structure 60 b. Preferably, each supportcomponent 61 b is not cemented to the hip bone and therefore isavailable for bone ingrowth into the textured outer surface 63 b of thesupport component 61 b. The support components 61 b may be arranged inany configuration that creates an access channel 68 b that extendsthrough the length of the periprosthetic support structure 60 b.Preferably, the support components 61 b are arranged to form asubstantially hemispherical support structure. It can be seen thatplacement of the support components 65 c precedes placement of anyprosthetic joint components.

After the periprosthetic support structure 60 b is constructed in abone, the acetabular cup implant 36 may be placed into the accesschannel 68 b of the periprosthetic support structure 60 b. Placement canoccur either during the same operative procedure as support component 61b placement or can be performed later once bone union to the supportcomponents 61 b has occurred. In either instance, the acetabular cupimplant 36 would be placed only after the acetabulum had beenreconstructed using the support structure 60 b. As shown in FIG. 23, atleast a portion of the outer surface 37 of the acetabular cup implant 36is secured to the inner surface 64 b (shown in phantom) of the accesschannel 68 b of the periprosthetic support structure 60 b with asuitable adhesive such as bone cement 38 (e.g., polymethylmethacrylate). It can be seen that the periprosthetic support structure60 b does not extend beyond a plane defined by the end surface 18 of theend portion 17 of the hip bone 14.

Because the periprosthetic support structure 60 b is not an integralcomponent of the acetabular cup implant 36, the periprosthetic supportstructure 60 b can be used with any acetabular cup implant 36 regardlessof manufacturer or prosthetic design. Further, it should be noted thatthe example given in FIGS. 18 and 23 relates to use of theperiprosthetic support structure 60 b in the acetabular cavity of a hipbone; however, other common sites where the periprosthetic supportstructure 60 b would be frequently used include the tibia and femur.Still other anatomic sites would include any joint that undergoesprosthetic arthroplasty when there is a significant metaphyseal bonedeficiency.

Referring now to FIGS. 19 and 21, there is shown yet another prostheticsystem according to the invention that includes an acetabular cupimplant 36 having an outer surface 37 and a periprosthetic supportstructure, indicated generally at 60 a, that is secured to the innersurface 16 of the acetabular cavity 15 of a hip bone 14. Theperiprosthetic support structure 60 a comprises two support components61 a having a configuration approximating a quarter of a sphere. Thesupport components 61 a of the periprosthetic support structure 60 a areimpacted and/or cemented into the inner surface 16 of the acetabularcavity 15 of a hip bone 14 in a spaced apart relationship.

Each support component 61 a may be formed from a metal alloy such astitanium alloys (e.g., titanium-6-aluminum-4-vanadium), cobalt-chromiumalloys, stainless steel alloys and tantalum alloys; nonresorbableceramics such as aluminum oxide and zirconia; nonresorbable polymericmaterials such as polyethylene; or composite materials such as carbonfiber-reinforced polymers (e.g., polysulfone). Preferably, each supportcomponent 61 a is formed from a metal alloy.

The outer surface 63 a of each support component 61 a may also beprovided with a metallic texture coating which provides a texturedsurface so as to attain the desired fixation (by way of tissue ingrowth)between each support component 61 a and the inner surface 16 of theacetabular cavity 15 of a hip bone 14 within which each supportcomponent 61 a is implanted. The inner surface 64 a of each supportcomponent 61 a has a rough or corrugated surface finish to facilitatethe interdigitation of bone cement. Likewise, the top end surface 62 aof each support component 61 a has a rough or corrugated surface finishto facilitate the interdigitation of bone cement.

Each support component 61 a may comprise any number of differentheights, widths and depths so that a surgeon is able to pick theappropriate sized support component for the patient after intraoperativeassessment and thereby avoid difficulties of size mismatch and bonegraft contouring. A surgeon can use conventional measurement tools toselect the size of each support component 61 a. The size, position andorientation of each support component 61 a is dependent on the size andlocation of the defects in the host bone as well as the quality of thebone that remains.

The support components 61 a may be implanted in a bone as follows toform the periprosthetic support structure 60 a. First, the acetabularcavity 15 of the hip bone 14 is inspected and tools (such as a reamer)may be used to clean material out of the acetabular cavity 15. Once theacetabular cavity 15 has been prepared, each support component 61 a isimpacted into or cemented onto the end portion 17 of the acetabularcavity 15 of the hip bone 14 in spaced apart relationship to form theperiprosthetic support structure 60 a. Preferably, each supportcomponent 61 a is not cemented to the hip bone and therefore isavailable for bone ingrowth into the textured outer surface 63 a of thesupport component 61 a. The support components 61 a may be arranged inany configuration that creates an access channel 68 a that extendsthrough the length of the periprosthetic support structure 60 a.Preferably, the support components 61 a are arranged to form asubstantially hemispherical support structure. It can be seen thatplacement of the support components 61 a precedes placement of anyprosthetic joint components.

After the periprosthetic support structure 60 a is constructed in abone, the acetabular cup implant 36 may be placed into the accesschannel 68 a of the periprosthetic support structure 60 a. Placement canoccur either during the same operative procedure as support component 61a placement or can be performed later once bone union to the supportcomponents 61 a has occurred. In either instance, the acetabular cupimplant 36 would be placed only after the acetabulum had beenreconstructed using the support structure 60 a. As shown in FIG. 21, atleast a portion of the outer surface 37 of the acetabular cup implant 36is secured to the inner surface 64 a (shown in phantom) of the accesschannel 68 a of the periprosthetic support structure 60 a with asuitable adhesive such as bone cement 38 (e.g., polymethylmethacrylate). It can be seen that the periprosthetic support structure60 a does not extend beyond a plane defined by the end surface 18 of theend portion 17 of the hip bone 14.

Because the periprosthetic support structure 60 a is not an integralcomponent of the acetabular cup implant 36, the periprosthetic supportstructure 60 a can be used with any acetabular cup implant 36 regardlessof manufacturer or prosthetic design. Further, it should be noted thatthe example given in FIGS. 19 and 21 relates to use of theperiprosthetic support structure 60 a in the acetabular cavity of a hipbone; however, other common sites where the periprosthetic supportstructure 60 a would be frequently used include the tibia and femur.Still other anatomic sites would include any joint that undergoesprosthetic arthroplasty when there is a significant metaphyseal bonedeficiency.

Referring now to FIGS. 20 and 22, there is shown yet another prostheticsystem according to the invention that includes an acetabular cupimplant 36 having an outer surface 37 and a periprosthetic supportstructure, indicated generally at 70, that is secured to the innersurface 16 of the acetabular cavity 15 of a hip bone 14. Theperiprosthetic support structure 70 comprises two support components 71having a configuration approximating a boomerang shape. The supportcomponents 71 of the periprosthetic support structure 70 are impacted,screwed and/or cemented into the inner surface 16 of the acetabularcavity 15 of a hip bone 14 in a spaced apart relationship.

Each support component 71 may be formed from a metal alloy such astitanium alloys (e.g., titanium-6-aluminum-4-vanadium), cobalt-chromiumalloys, stainless steel alloys and tantalum alloys; nonresorbableceramics such as aluminum oxide and zirconia; nonresorbable polymericmaterials such as polyethylene; or composite materials such as carbonfiber-reinforced polymers (e.g., polysulfone). Preferably, each supportcomponent 71 is formed from a metal alloy.

The outer surface 73 of each support component 71 may also be providedwith a metallic texture coating which provides a textured surface so asto attain the desired fixation (by way of tissue ingrowth) between eachsupport component 71 and the inner surface 16 of the acetabular cavity15 of a hip bone 14 within which each support component 71 is implanted.The inner surface 74 of each support component 71 has a rough orcorrugated surface finish to facilitate the interdigitation of bonecement. Likewise, the top end surface 72 of each support component 71has a rough or corrugated surface finish to facilitate theinterdigitation of bone cement. Each support component 71 may compriseany number of different heights, widths and depths so that a surgeon isable to pick the appropriate sized support component for the patientafter intraoperative assessment and thereby avoid difficulties of sizemismatch and bone graft contouring. A surgeon can use conventionalmeasurement tools to select the size of each support component 71.

The support components 71 may be implanted in a bone as follows to formthe periprosthetic support structure 70. First, the acetabular cavity 15of the hip bone 14 is inspected and tools (such as a reamer) may be usedto clean material out of the acetabular cavity 15. Once the acetabularcavity 15 has been prepared, each support component 71 is placed into,impacted into, or cemented onto the end portion 17 of the acetabularcavity 15 of the hip bone 14 in spaced apart relationship to form theperiprosthetic support structure 70. The support components 71 shown inFIGS. 20 and 22 are screwed into the hip bone 14 using screws 67 (shownin phantom in FIG. 22). The support components 71 may be arranged in anyconfiguration that creates an access channel 77 that extends through thelength of the periprosthetic support structure 70. The size, positionand orientation of each support component 71 is dependent on the sizeand location of the defepts in the host bone as well as the quality ofthe bone that remains.

After the periprosthetic support structure 70 is constructed in a bone,the acetabular cup implant 36 may be placed into the access channel 77of the periprosthetic support structure 70. Placement can occur eitherduring the same operative procedure as support component 71 placement orcan be performed later once bone union to the support components 71 hasoccurred. In either instance, the acetabular cup implant 36 would beplaced only after the acetabulum had been reconstructed using thesupport structure 70. As shown in FIG. 22, at least a portion of theouter surface 37 of the acetabular cup implant 36 is secured to theinner surface 74 (shown in phantom) of the access channel 77 of theperiprosthetic support structure 70 with a suitable adhesive such asbone cement 38 (e.g., polymethyl methacrylate). It can be seen that theperiprosthetic support structure 70 does not extend beyond a planedefined by the end surface 18 of the end portion 17 of the hip bone 14.

Because the periprosthetic support structure 70 is not an integralcomponent of the acetabular cup implant 36, the periprosthetic supportstructure 70 can be used with any acetabular cup implant 36 regardlessof manufacturer or prosthetic design. Further, it should be noted thatthe example given in FIGS. 20 and 22 relates to use of theperiprosthetic support structure 70 in the acetabular cavity of a hipbone; however, other common sites where the periprosthetic supportstructure 70 would be frequently used include the tibia and femur. Stillother anatomic sites would include any joint that undergoes prostheticarthroplasty when there is a significant metaphyseal bone deficiency.

Therefore, the present invention provides prosthetic implant supportstructures that solve the problems associated with the loss of strongbone stock near a joint being replaced with a prosthesis. The describedprosthetic implant support structures do not rely on the use of largeamounts of bone graft or cumbersome bone graft delivery devices. Theprosthetic implant support structures can eliminate the need to cementthe distal portion of the stem of an implant to the inner surface of abone cavity and can be used with a wide variety of prosthetic implantsobtained from any number of different implant manufacturers.Furthermore, the described prosthetic implant system can optimizeimplant support on intact host bone with minimal removal of residualhost bone and encourages bone ingrowth and attachment over as large asurface area as possible.

While the implantation of tibial, femoral, and acetabular prostheses hasbeen illustrated and described herein, one skilled in the art willappreciate that the present invention can be practiced by other than thedescribed embodiments, which have been presented for purposes ofillustration and not of limitation. For instance, the methods andprostheses according to the invention can be used in the repair of anybone or in connection with the implantation of prosthetic devices at orin any bone in the body. Accordingly, the scope of the appended claimsshould not be limited to the description of the embodiments containedherein.

What is claimed is:
 1. A prosthetic system for implantation in a cavityin an end of a bone, the prosthetic system comprising: a prostheticimplant; and a support structure for occupying an area in a cavity in anend of a bone, the support structure formed separately from saidprosthetic implant for subsequent connection to said prosthetic implant,said support structure consisting essentially of a porous metal alloyand capable of being impacted and wedged, by itself, into the cavity inthe end of the bone for obtaining a press fit of the support structurein the cavity prior to connecting said support structure to saidprosthetic implant, the support structure having a support structureinner surface defining an axial channel having an axial extent thatextends through the length of the support structure, wherein said porousmetal alloy is a bone ingrowth-receptive material with a porousstructure for encouraging bone ingrowth and attachment throughout thesupport structure for restoring lost bone stock in the cavity in the endof the bone in the area occupied by the support structure when thesupport structure is implanted in the cavity in the end of the bone,wherein the prosthetic implant is receivable in the axial channel of thesupport structure such that a portion of the prosthetic implant extendsthrough the axial channel of the support structure and is securable tothe inner surface of the support structure by an adhesive disposedbetween the prosthetic implant and the support structure along the axialchannel of the support structure.
 2. The prosthetic system of claim 1wherein: the support structure has an end surface which surrounds theaxial channel at a first end of the support structure, and a portion ofthe prosthetic implant is secured to the end surface of the supportstructure by an adhesive.
 3. The prosthetic system of claim 1 wherein:the prosthetic implant has a body and an attached stem extending awayfrom the body, and at least a portion of an outer surface of the stem ofthe prosthetic implant is received in the axial channel of the supportstructure and is secured to the inner surface of the support structureby the adhesive.
 4. The prosthetic system of claim 3 wherein: at least aportion of the outer surface of the stem adjacent a distal end of thestem of the prosthetic implant is securable to an inner surface of thecavity in the end of the bone.
 5. The prosthetic system of claim 1wherein: at least a portion of the inner surface of the supportstructure is textured.
 6. The prosthetic system of claim 1 wherein: atleast a portion of an end surface of the support structure adjacent afirst end of the support structure is textured.
 7. The prosthetic systemof claim 1 wherein: a perimeter region of a bearing surface of theprosthetic implant is securable to an end surface of the bone.
 8. Theprosthetic system of claim 1 wherein: the support structure is a hollowsleeve having a sloped outer surface with a first end of the hollowsleeve having a comparatively larger perimeter than an opposite secondend of the hollow sleeve.
 9. The prosthetic system of claim 1 wherein:the support structure is formed from a porous metal alloy selected fromthe group consisting of titanium alloys, cobalt-chromium alloys,stainless steel alloys and tantalum alloys.
 10. The prosthetic system ofclaim 1 wherein: the support structure is formed from a porous tantalumalloy.
 11. The prosthetic system of claim 1 wherein the supportstructure comprises: a hollow cylindrical sleeve.
 12. The prostheticsystem of claim 11 wherein: the sleeve includes two sections, one of thesections having a smaller outside diameter.
 13. The prosthetic system ofclaim 11 wherein: the prosthetic implant has a body and a stem extendingaway from the body, and at least a portion of an outer surface of thestem of the prosthetic implant is received in the axial channel of thesupport structure and is secured to the inner surface of the supportstructure by the adhesive.
 14. A prosthetic system for implantation in acavity in an end of a bone, the prosthetic system comprising: aprosthetic implant having a body which forms part of a mechanical jointand an attached stem extending away from the body; and a hollow sleevefor occupying an area in a cavity in an end of a bone, the hollow sleeveformed separately from said prosthetic implant for subsequent connectionto said prosthetic implant, said hollow sleeve consisting essentially ofa porous metal alloy and capable of being impacted and wedged, byitself, into the cavity in the end of the bone for obtaining a press fitof the hollow sleeve in the cavity prior to connecting said hollowsleeve to said prosthetic implant, said hollow sleeve having a sleeveinner surface which defines an axial channel that extends through thelength of the sleeve, the sleeve being securable to an inner surfaceforming the cavity in the end of the bone, wherein said porous metalalloy is a bone ingrowth-receptive material with a porous structure forencouraging bone ingrowth and attachment throughout the hollow sleevefor restoring lost bone stock in the cavity in the end of the bone inthe area occupied by the hollow sleeve when the hollow sleeve isimplanted in the cavity in the end of the bone, wherein at least aportion of an outer surface of the stem of the prosthetic implant isreceivable in the axial channel of the sleeve and is securable to thesleeve inner surface by an adhesive.
 15. The prosthetic system of claim14 wherein: the hollow sleeve is formed from a porous metal alloyselected from the group consisting of titanium alloys, cobalt-chromiumalloys, stainless steel alloys and tantalum alloys.
 16. The prostheticsystem of claim 14 wherein: the hollow sleeve includes a firstlongitudinal section with a comparatively smaller diameter than a secondlongitudinal section of the hollow sleeve.
 17. The prosthetic system ofclaim 14 wherein: the hollow sleeve is formed from a porous tantalumalloy.
 18. The prosthetic system of claim 1 wherein: the adhesive isbone cement.
 19. The prosthetic system of claim 14 wherein: the adhesiveis bone cement.
 20. A prosthetic system for implantation in a cavity inan end of a bone, the prosthetic system comprising: a prosthetic implanthaving a body which forms part of a mechanical joint and an attachedstem extending away from the body; a hollow sleeve for occupying an areain a cavity in an end of a bone, the hollow sleeve formed separatelyfrom said prosthetic implant for subsequent connection to saidprosthetic implant, said hollow sleeve consisting essentially of aporous metal alloy and capable of being impacted and wedged, by itself,into the cavity in the end of the bone for obtaining a press fit of thehollow sleeve in the cavity prior to connecting said hollow sleeve tosaid prosthetic implant, said hollow sleeve having a sleeve innersurface which defines an axial channel that extends through the lengthof the sleeve, the sleeve being securable to an inner surface formingthe cavity in the end of the bone, wherein said porous metal alloy is abone ingrowth-receptive material with a porous structure for encouragingbone ingrowth and attachment throughout the hollow sleeve for restoringlost bone stock in the cavity in the end of the bone in the areaoccupied by the hollow sleeve when the hollow sleeve is implanted in thecavity in the end of the bone, with at least a portion of an outersurface of the stem of the prosthetic implant receivable in the axialchannel of the sleeve; and a quantity of bone cement situated betweenthe outer surface of the stem and the sleeve inner surface for securingthe stem to the sleeve inner surface.
 21. The prosthetic system of claim1 wherein said support structure is a hollow sleeve including a firstlongitudinal section with a comparatively smaller diameter than a secondlongitudinal section of the hollow sleeve.
 22. The prosthetic system ofclaim 1, wherein the support structure is formed entirely with saidporous metal alloy.
 23. The prosthetic system of claim 1, wherein thesupport structure has an established size and shape when unconnected tosaid prosthetic implant.
 24. The prosthetic system of claim 14 whereinthe hollow sleeve is formed entirely with said porous metal alloy. 25.The prosthetic system of claim 14, wherein the hollow sleeve has anestablished size and shape when unconnected to said prosthetic implant.26. The prosthetic system of claim 20, wherein the hollow sleeve isformed entirely with said porous metal alloy.
 27. The prosthetic systemof claim 20, wherein the hollow sleeve has an established size and shapewhen unconnected to said prosthetic implant.
 28. The prosthetic systemof claim 1, wherein the support structure has an external geometryimplantable in the cavity in the end of the bone, and wherein thesupport structure, despite consisting essentially of said porous metalallow, is capable of being impacted and wedged, by itself, into thecavity for obtaining a press fit of said external geometry within thebone.
 29. The prosthetic system of claim 14, wherein the hollow sleevehas an external geometry implantable in the cavity in the end of thebone, and wherein the hollow sleeve, despite consisting essentially ofsaid porous metal alloy, is capable of being impacted and wedged, byitself, into the cavity for obtaining a press fit of said externalgeometry within the bone.
 30. The prosthetic system of claim 20, whereinthe hollow sleeve has an external geometry implantable in the cavity inthe end of the bone, and wherein the hollow sleeve, despite consistingessentially of said porous metal alloy, is capable of being impacted andwedged, by itself, into the cavity for obtaining a press fit of saidexternal geometry within the bone.